Heated calender rollers, which use heated fluid flowing through their interiors, are known in the art. Similarly, chilled or quenching rollers often employ chilled fluid in their interiors. U.S. Pat. No. 4,050,510, issued to Theysohn, discloses a shell of chilled cast iron having a plurality of passages parallel to the axis of the shell. Two cast iron end structures support the two ends of the shell. A plurality of radial passages is provided in the end structures for guiding a heating medium such as steam outward to, and inward from, the passages in the shell.
U.S. Pat. No. 4,077,466, issued to Fleissner, discloses a heated roller having an outer cylindrical shell, an inner cylindrical shell, a wall defining an annular space between the two shells, partitions in the annular space for forming flow channels for a heating medium, and radially disposed channels in the ends of the shell for introducing and removing the heating medium to and from the flow channels. U.S. Pat. No. 3,135,319, issued to Richards, discloses a similar configuration in a leveling roller.
In a point bonding process for nonwoven materials, fabric is passed between two heated rollers that are nipped together under pressures of 100–1000 pounds per linear inch. Again, a common way of heating the rollers is to pass a heated heat transfer fluid through the roll journals at one or both ends, and through the annulus between an outer roll shell in contact with the nonwoven web, and an inner shell. The annulus channels the oil at high velocity (with a high heat transfer coefficient) along the inner surface of the outer shell. Commonly, disk shaped chambers at both ends of the shell are used to introduce and remove the heat transfer fluid in a radial direction between the roll journals and the annulus.
Rotation of the rolls at high velocity can cause the fluid in the end chambers to move in an angular or spiral fashion. Imparting and dissipating rotational energy in the fluid causes a disturbance in the fluid flow, resulting in a loss in fluid volume being pumped at a constant pumping pressure. There is a resulting loss in heat transfer, and a loss in bonding capability and speed.
Angular and spiral flow can be overcome by providing radially directed channels, as in the references discussed above. However, the disclosed channels are few, and are increasingly spaced apart as they approach the outer surface of the roller. Due to the spaces between the radial channels, the heat transfer fluid is not evenly distributed as it enters the annulus.
There is a need or desire for a fluid distribution system in a heated roller which substantially overcomes angular and spiral fluid motion while providing a substantially even distribution of heat transfer fluid to and from the annulus.